1. Field of the Invention
The present invention relates to a water detecting system for protecting electronic circuitry of a portable electric device when water enters the portable electric device.
2. Description of the Prior Art
As portable electric devices such as mobile phones, personal digital assistants (PDAs), and notebook computers become a bigger part of people's lives, it also becomes more important to limit the damage caused to these portable electric devices from exposure to water. It is well known that water has the potential to damage electric devices. When the electric devices are operating at the time that they are exposed to water, the damage can be especially severe. Water can short circuit electronic circuitry that is in use, causing irreparable damage to the electronic circuitry.
The traditional defense against water damage is to seal off all openings of the electric device to make the electric device waterproof. Please refer to FIG. 1. FIG. 1 is a cross section diagram of a water proofing system 10 according to the prior art. The water proofing system 10 shown is used for sealing keys 18 of an electric device's keypad for preventing water from entering the electric device through openings in the keypad. Each key 18 is covered with a waterproof boot 12. Each waterproof boot 12 contains a dome section 14 and a foot 16. The dome section 14 is flexible, and can be pressed downward for allowing a user to press the keys 18 of the electric device. Since all openings in the keypad are completely covered by the water proof boots 12, the water proofing system 10 protects the electric device from water damage.
Unfortunately, the water proofing system 10 shown in FIG. 1 is expensive to produce and use of the water proofing system 10 makes it difficult to reduce the size of the electric devices utilizing it. Moreover, if water is able to enter into the electric devices through other openings or cracks in the housing of the electric device that have not been waterproofed, the electronic circuitry of the electric device may still become damaged. That is, the water proofing system 10 provides no protection for the electronic circuitry of the electric device when water permeates through the outer housing of the electric device and does not detect that water has entered the outer housing.